Software Defined Radio Based Frequency Modulated Continuous Wave Ground Penetrating Radar

Frequency modulated continuous wave (FMCW) radar allows for a wide range of research applications. One primary use of this technology and what is explored in this thesis, is imaging in the form of ground penetrating radar. To generate proper results, spectral wide-band reconstruction has been developed to overcome hardware limitations allowing for high resolution radar. Requiring complex reconstruction algorithms, the proposed method benefits greatly in terms of performance and implementation compared to other radar systems. This thesis develops a wideband linearly frequency modulated radar leveraging a software-defined radio (SDR). The modular system is capable of a tunable wideband bandwidth up to the maximum SDR ratings. This high-resolution system is further improved through implementation of grating side-lobe suppression filters that correct for the spectral discontinuities imposed by the reconstruction. These grating lobes are managed through multiple techniques to alleviate any ghost imaging or false positives associated with object detection. The solution provided allows for generally non-coherent devices to operate with synchronous phase giving accurate sample-level measurements. Various corrections are in place as mitigation of hardware transfer functions and system level noise. First the system was theorized and simulated, illuminating the performance of the radar. Following development of the radar, measurements were conducted to confirm proper and accurate object detection. Further experiments were performed ensuring Ground Penetrating Radar (GPR) performance as designed. Applications of this work include Synthetic Aperture Radar (SAR) imaging, innovative GPR, and unmanned aerial vehicle (UAV) systems

An introduction to the interim digital SAR processor and the characteristics of the associated Seasat SAR imagery

Basic engineering data regarding the Interim Digital SAR Processor (IDP) and the digitally correlated Seasat synthetic aperature radar (SAR) imagery are presented. The correlation function and IDP hardware/software configuration are described, and a preliminary performance assessment presented. The geometric and radiometric characteristics, with special emphasis on those peculiar to the IDP produced imagery, are described

실시간 근거리 영상화를 위한 MIMO 역합성 개구 레이더 시스템

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 남상욱.Microwave and millimeter wave (micro/mmW) imaging systems have advantages over other imaging systems in that they have penetration properties over non-metallic structures and non-ionization. However, these systems are commercially applicable in limited areas. Depending on the quality and size of the images, a system can be expensive and images cannot be provided in real-time. To overcome the challenges of the current micro/mmW imaging system, it is critical to suggest a new system concept and prove its potential benefits and hazards by demonstrating the testbed. This dissertation presents Ku1DMIC, a wide-band micro/mmW imaging system using Ku-band and 1D-MIMO array, which can overcome the challenges above. For cost-effective 3D imaging capabilities, Ku1DMIC uses 1D-MIMO array configuration and inverse synthetic aperture radar (ISAR) technique. At the same time, Ku1DMIC supports real-time data acquisition through a system-level design of a seamless interface with frequency modulated continuous wave (FMCW) radar. To show the feasibility of 3D imaging with Ku1DMIC and its real-time capabilities, an accelerated imaging algorithm, 1D-MIMO-ISAR RSA, is proposed and demonstrated. The detailed contributions of the dissertation are as follows. First, this dissertation presents Ku1DMIC – a Ku-band MIMO frequency-modulated continuous-wave (FMCW) radar experimental platform with real-time 2D near-field imaging capabilities. The proposed system uses Ku-band to cover the wider illumination area given the limited number of antennas and uses a fast ramp and wide-band FMCW waveform for rapid radar data acquisition while providing high-resolution images. The key design aspect behind the platform is stability, reconfigurability, and real-time capabilities, which allows investigating the exploration of the system’s strengths and weaknesses. To satisfy the design aspect, a digitally assisted platform is proposed and realized based on an AMD-Xilinx UltraScale+ Radio Frequency System on Chip (RFSoC). The experimental investigation for real-time 2D imaging has proved the ability of video-rate imaging at around 60 frames per second. Second, a waveform digital pre-distortion (DPD) method and calibration method are proposed to enhance the image quality. Even if a clean FMCW waveform is generated with the aid of the optimized waveform generator, the signal will inevitably suffer from distortion, especially in the RF subsystem of the platform. In near-field imaging applications, the waveform DPD is not effective at suppressing distortion in wide-band FMCW radar systems. To solve this issue, the LO-DPD architecture and binary search based DPD algorithm are proposed to make the waveform DPD effective in Ku1DMIC. Furthermore, an image-domain optimization correction method is proposed to compensate for the remaining errors that cannot be eliminated by the waveform DPD. For robustness to various unwanted signals such as noise and clutter signals, two regularized least squares problems are applied and compared: the generalized Tikhonov regularization and the total variation (TV) regularization. Through various 2D imaging experiments, it is confirmed that both methods can enhance the image quality by reducing the sidelobe level. Lastly, the research is conducted to realize real-time 3D imaging by applying the ISAR technique to Ku1DMIC. The realization of real-time 3D imaging using 1D-MIMO array configuration is impactful in that this configuration can significantly reduce the costs of the 3D imaging system and enable imaging of moving objects. To this end, the signal model for the 1D-MIMO-ISAR configuration is presented, and then the 1D-MIMO-ISAR range stacking algorithm (RSA) is proposed to accelerate the imaging reconstruction process. The proposed 1D-MIMO-ISAR RSA can reconstruct images within hundreds of milliseconds while maintaining almost the same image quality as the back-projection algorithm, bringing potential use for real-time 3D imaging. It also describes strategies for setting ROI, considering the real-world situations in which objects enter and exit the field of view, and allocating GPU memory. Extensive simulations and experiments have demonstrated the feasibility and potential benefits of 1D-MIMO-IASR configuration and 1D-MIMO-ISAR RSA.마이크로파 및 밀리미터파(micro/mmW) 영상화 시스템은 비금속 구조 및 비이온화에 비해 침투 특성이 있다는 점에서 다른 이미징 시스템에 비해 장점이 있다. 그러나 이러한 시스템은 제한된 영역에서만 상업적으로 적용되고 있다. 이미지의 품질과 크기에 따라 시스템이 매우 고가일 수 있으며 이미지를 실시간으로 제공할 수 없는 현황이다. 현재의 micro/mmW 이미징 시스템의 문제를 극복하려면 새로운 시스템 개념을 제안하고 테스트베드를 시연하여 잠재적인 이점과 위험을 입증하는 것이 중요하다. 본 논문에서는 Ku-band와 1D-MIMO 어레이를 이용한 광대역 micro/mmW 이미징 시스템인 Ku1DMIC를 제안하여 위와 같은 문제점을 극복할 수 있다. 비용 효율적인 3차원 영상화 기능을 위해 Ku1DMIC는 1D-MIMO 배열 기술과 ISAR(Inverse Synthetic Aperture Radar) 기술을 사용한다. 동시에 Ku1DMIC는 주파수 변조 연속파 (FMCW) 레이더와의 원활한 인터페이스의 시스템 수준 설계를 통해 실시간 데이터 수집을 지원한다. Ku1DMIC를 사용한 3차원 영상화의 구현 및 실시간 기능의 가능성을 보여주기 위해, 2차원 영상화를 위한 1D-MIMO RSA과 3차원 영상화를 위한 1D-MIMO-ISAR RSA가 제안되고 Ku1DMIC에서 구현된다. 따라서, 본 학위 논문의 주요 기여는 Ku-band 1D-MIMO 배열 기반 영상화 시스템 프로토타입을 개발 및 테스트하고, ISAR 기반 3차원 영상화 기능을 검사하고, 실시간 3차원 영상화 가능성을 조사하는 것이다. 이에 대한 세부적인 기여 항목은 다음과 같다. 첫째, 실시간 2D 근거리장 이미징 기능을 갖춘 Ku 대역 MIMO 주파수 변조 연속파(FMCW) 레이더 실험 플랫폼인 Ku1DMIC를 제시한다. 제안하는 시스템은 제한된 수의 안테나에서 더 넓은 조명 영역을 커버하기 위해 Ku 대역을 사용하고 고해상도 이미지를 제공하면서 빠른 레이더 데이터 수집을 위해 고속 램프 및 광대역 FMCW 파형을 사용한다. 플랫폼의 핵심 설계 원칙은 안정성, 재구성 가능성 및 실시간 기능으로 시스템의 강점과 약점을 광범위하게 탐색한다. 설계 원칙을 만족시키기 위해 AMD-Xilinx UltraScale+ RFSoC(Radio Frequency System on Chip)를 기반으로 디지털 지원 플랫폼을 제안하고 구현한다. 실시간 2D 이미징에 대한 실험적 조사는 초당 약 60프레임에서 비디오 속도 이미징의 능력을 입증했다. 둘째, 영상 품질 향상을 위한 파형 디지털 전치왜곡(DPD) 방법과 보정 방법을 제안한다. 최적화된 파형 발생기의 도움으로 깨끗한 FMCW 파형이 생성되더라도 특히 플랫폼의 RF 하위 시스템에서 신호는 필연적으로 왜곡을 겪게된다. 근거리 영상화 응용 분야에서는 파형 DPD는 광대역 FMCW 레이더 시스템의 왜곡을 억제하는 데 효과적이지 않다. 이 문제를 해결하기 위해 Ku1DMIC에서 파형 DPD가 유효하도록 LO-DPD 아키텍처와 이진 탐색 기반 DPD 알고리즘을 제안한다. 또한, 파형 DPD로 제거할 수 없는 나머지 오류를 보상하기 위해 이미지 영역 최적화 보정 방법을 제안한다. 노이즈 및 클러터 신호와 같은 다양한 원치 않는 신호에 대한 견고성을 위해 일반화된 Tikhonov 정규화 및 전체 변동(TV) 정규화라는 두 가지 정규화된 최소 자승 문제를 적용 후 비교한다. 다양한 2차원 영상화 실험을 통해 두 방법 모두 부엽 레벨을 줄여 화질을 향상시킬 수 있음을 확인한다. 마지막으로, ISAR 기법을 2차원 영상 플랫폼에 적용하여 실시간 3차원 영상을 구현하기 위한 연구를 진행한다. 1D-MIMO-ISAR 구성에서 실시간 3D 이미징의 구현은 이러한 구성이 3D 이미징 시스템의 비용을 크게 줄일 수 있다는 점에서 영향력이 있다. 따라서 이 논문에서는 1D-MIMO-ISAR 구성에 대한 이미징 재구성을 가속화하기 위해 1D-MIMO-ISAR 범위 스태킹 알고리즘(RSA)을 제안한다. 제안된 1D-MIMO-ISAR RSA는 널리 알려진 Back-Projection 알고리즘과 거의 동일한 이미지 품질을 유지하면서도 수백 밀리초 이내에 이미지를 재구성함으로써 실시간 영상화에 대한 가능성을 보여준다. 또한 물체가 시야에 들어오고 나가는 실제 상황을 고려하기 위한 ROI 설정, 그리고 메모리 할당에 대한 전략을 설명한다. 광범위한 시뮬레이션과 실험을 통해 1D-MIMO-IASR 구성 및 1D-MIMO-ISAR RSA의 가능성과 잠재적 이점을 확인한다.1 INTRODUCTION 1 1.1 Microwave and millimeter-wave imaging 1 1.2 Imaging with radar system 2 1.3 Challenges and motivation 5 1.4 Outline of the dissertation 8 2 FUNDAMENTAL OF TWO-DIMENSIONAL IMAGING USING A MIMO RADAR 9 2.1 Signal model 9 2.2 Consideration of waveform 12 2.3 Image reconstruction algorithm 16 2.3.1 Back-projection algorithm 16 2.3.2 1D-MIMO range-migration algorithm 20 2.3.3 1D-MIMO range stacking algorithm 27 2.4 Sampling criteria and resolution 31 2.5 Simulation results 36 3 MIMO-FMCW RADAR IMPLEMENTATION WITH 16 TX - 16 RX ONE- DIMENSIONAL ARRAYS 46 3.1 Wide-band FMCW waveform generator architecture 46 3.2 Overall system architecture 48 3.3 Antenna and RF transceiver module 53 3.4 Wide-band FMCW waveform generator 55 3.5 FPGA-based digital hardware design 63 3.6 System integration and software design 71 3.7 Testing and measurement 75 3.7.1 Chirp waveform measurement 75 3.7.2 Range profile measurement 77 3.7.3 2-D imaging test 79 4 METHODS OF IMAGE QUALITY ENHANCEMENT 84 4.1 Signal model 84 4.2 Digital pre-distortion of chirp signal 86 4.2.1 Proposed DPD hardware system 86 4.2.2 Proposed DPD algorithm 88 4.2.3 Measurement results 90 4.3 Robust calibration method for signal distortion 97 4.3.1 Signal model 98 4.3.2 Problem formulation 99 4.3.3 Measurement results 105 5 THREE-DIMENSIONAL IMAGING USING 1-D ARRAY SYSTEM AND ISAR TECHNIQUE 110 5.1 Formulation for 1D-MIMO-ISAR RSA 111 5.2 Algorithm implementation 114 5.3 Simulation results 120 5.4 Experimental results 122 6 CONCLUSIONS AND FUTURE WORK 127 6.1 Conclusions 127 6.2 Future work 129 6.2.1 Effects of antenna polarization in the Ku-band 129 6.2.2 Forward-looking near-field ISAR configuration 130 6.2.3 Estimation of the movement errors in ISAR configuration 131 Abstract (In Korean) 145 Acknowlegement 148박

A Synthetic Bandwidth Method for High-Resolution SAR Based on PGA in the Range Dimension

The synthetic bandwidth technique is an effective method to achieve ultra-high range resolution in an SAR system. There are mainly two challenges in its implementation. The first one is the estimation and compensation of system errors, such as the timing deviation and the amplitude-phase error. Due to precision limitation of the radar instrument, construction of the sub-band signals becomes much more complicated with these errors. The second challenge lies in the combination method, that is how to fit the sub-band signals together into a much wider bandwidth. In this paper, a novel synthetic bandwidth approach is presented. It considers two main errors of the multi-sub-band SAR system and compensates them by a two-order PGA (phase gradient auto-focus)-based method, named TRPGA. Furthermore, an improved cut-paste method is proposed to combine the signals in the frequency domain. It exploits the redundancy of errors and requires only a limited amount of data in the azimuth direction for error estimation. Moreover, the up-sampling operation can be avoided in the combination process. Imaging results based on both simulated and real data are presented to validate the proposed approach

Cassini RADAR Sequence Planning and Instrument Performance

The Cassini RADAR is a multimode instrument used to map the surface of Titan, the atmosphere of Saturn, the Saturn ring system, and to explore the properties of the icy satellites. Four different active mode bandwidths and a passive radiometer mode provide a wide range of flexibility in taking measurements. The scatterometer mode is used for real aperture imaging of Titan, high-altitude (around 20 000 km) synthetic aperture imaging of Titan and Iapetus, and long range (up to 700 000 km) detection of disk integrated albedos for satellites in the Saturn system. Two SAR modes are used for high- and medium-resolution (300-1000 m) imaging of Titan's surface during close flybys. A high-bandwidth altimeter mode is used for topographic profiling in selected areas with a range resolution of about 35 m. The passive radiometer mode is used to map emission from Titan, from Saturn's atmosphere, from the rings, and from the icy satellites. Repeated scans with differing polarizations using both active and passive data provide data that can usefully constrain models of surface composition and structure. The radar and radiometer receivers show very good stability, and calibration observations have provided an absolute calibration good to about 1.3 dB. Relative uncertainties within a pass and between passes can be even smaller. Data are currently being processed and delivered to the planetary data system at quarterly intervals one year after being acquired

FMCW Radar signal processing for Antarctic Ice Shelf profiling and imaging

This thesis contains details of all the signal processing work being done on FMCW Radar (operating at VHF-UHF band) for the Antarctic Ice Shelf monitoring project that has been carried out at UCL. The system developed at UCL was based on a novel concept of phase-sensitive FMCW radar with low power consumption, thus allowing data collection for long period of time with millimetre range precision. Development of new signal processing method was required in order to process the large amount of data, along with the signal processing technique for obtaining the high precision range values. This was achieved during the first stage of the thesis, providing accurate ice shelf basal layer melt rate values. Properties of the FMCW radar system and experimental scenarios posed further signal processing challenges. Those challenges were met by developing number of novel algorithms. A novel shape matching algorithm was developed to detect internal layers underneath the ice shelf. Range migration correction method was developed to compensate for the defocusing of the image in large angles due to high fractional bandwidth of the radar system. Vertical error correction method was developed to compensate for any vertical displacement of the radar antenna during field experiment. Finally, a novel 3-D MIMO imaging algorithm for the Antarctic ice shelf base study was developed. This was done to process the 8x8 MIMO radar (developed at UCL) data. The radars have been deployed in the Antarctica during the Austral summer of each year from 2011-2014. The field experiments were done in the Ronne, Larsen-C, Larsen North, George VI and Ross ice shelves. The novel signal processing techniques have been successfully applied on the real data, allowing better understanding of the Antarctic ice shelf features

Spaceborne synthetic-aperture imaging radars: Applications, techniques, and technology

In the last four years, the first two Earth-orbiting, space-borne, synthetic-aperture imaging radars (SAR) were successfully developed and operated. This was a major achievement in the development of spaceborne radar sensors and ground processors. The data acquired with these sensors extended the capability of Earth resources and ocean-surface observation into a new region of the electromagnetic spectrum. This paper is a review of the different aspects of spaceborne imaging radars. It includes a review of: 1) the unique characteristics of space-borne SAR systems; 2) the state of the art in spaceborne SAR hardware and SAR optical and digital processors; 3) the different data-handling techniques; and 4) the different applications of spaceborne SAR data

Low-cost CW-LFM radar sensor at 100 GHz

This paper presents a W-band high-resolution radar sensor for short-range applications. Low-cost technologies have been properly selected in order to implement a versatile and easily scalable radar system. A large operational bandwidth of 9 GHz, required for obtaining high-range resolution, is attained by means of a frequency multiplication-based architecture. The system characterization to identify the performance-limiting stages and the subsequent design optimization are presented. The assessment of system performance for several representative applications has been carried out

Analysis and implementation of low fidelity radar-based remote sensing for unmanned aircraft systems

Radar-based remote sensing is consistently growing, and new technologies and subsequent techniques for characterization are changing the feasibility of understanding the environment. The emergence of easily accessible unmanned aircraft system (UAS) has broadened the scope of possibilities for efficiently surveying the world. The continued development of low-cost sensing systems has greatly increased the accessibility to characterize physical phenomena. In this thesis, we explore the viability and implementation of using UAS as a means of radar-based remote sensing for ground penetrating radar (GPR) and polarimetric scatterometry. Additionally, in this thesis, we investigate the capabilities and implementations of low-cost microwave technologies for applications in radar-based remote sensing compared to higher fidelity and more expensive technologies of similar scope

Contribution to ground-based and UAV SAR systems for Earth observation

Mankind's way of life is the main driver of a planetary-scale change that is marked by the growing of human population's demand of energy, food, goods, services and information. As a result, it have emerged new ecological, economical, social and geopolitical concerns. In this scenario, SAR remote sensing is a potential tool that provides unique information about the Earth's properties and processes that can be used to solve societal challenges of local and global dimension. SARs, which are coherent systems that are able to provide high resolution images with weather independence, represent a suitable alternative for EO with diverse applications. Some examples of SAR application areas are topography (DEM generation with interferometry), agriculture (crop classification or soil moisture), or geology (monitoring surface deformation). In this framework, the encompassing objective of the present doctoral work has been part of the implementation and the subsequent evaluation of capabilities of two X-band SAR sensors. On the one hand, the RISKSAR-X radar designed to be operated at ground to monitor small-scale areas of observation and, on the other, the ARBRES-X sensor designed to be integrated into small UAVs. Despite its inherently dissimilar conception, the concurrence of both sensors has been evidenced along this manuscript. By taking advantage of the similarities between them, it has been possible to analogously assess both sensors to obtain conclusions. In this context, the common link has been the development of the polarimetric OtF operation mode of the RISKSAR-X, allowing this sensor to be operated equivalently to the ARBRES-X. Regarding the RISKSAR-X SAR sensor, several hardware contributions have been developed during part of this Ph.D. with the aim of improving the system performance. By endowing the system with the capability to operate in the fully polarimetric OtF acquisition mode, the relative long scanning time has been reduced. It is of great interest since the measured scatterers that present a short term variable reflectivity during the scanning time, such as moving vegetation, may degrade the extracted parameters from the retrieved data and the SAR image reconstruction. During this doctoral activity, it has been studied the image blurring, the decorrelation and the coherence degradation introduced by this effect. Furthermore, a new term in the differential interferometric coherence that takes into account the image blurring has been introduced. Concerning the ARBRES-X SAR system, one of the main objectives pursued during this Ph.D. has been the integration of the sensor into a small UAV MP overcoming restrictions of weight, size and aerodynamics of the platform. The use of this type of platforms is expected to open up new possibilities in airborne SAR remote sensing, since it offers much more versatility than the commonly used fixed wings UAVs. Different innovative flight strategies with this type of platforms have been assessed and some preliminary results have been obtained with the use of the ARBRES-X SAR system. During the course of the present doctoral work, much effort has been devoted to achieve the first experimental repeat-pass interfereometric results obtained with the UAV MP together with the ARBRES-X. Moreover, the sensor has been endowed with fully polarimetric capabilities by applying the improvements developed to the RISKSAR-X radar, which is another example of the duality between both systems. Finally, a vertical and a semicircular aperture have been successfully performed obtaining SLC images of the scenario, which envisages the capability of the UAV MP to perform tomographic images and complete circular apertures in the future. In conclusion, the UAV MP is a promising platform that opens new potentials for several applications, such as repeat-pass interferometry or differential tomography imaging with the realization of almost arbitrary trajectories.El mode de viure de la humanitat és el principal motor d'un canvi a escala planetària que està marcat per la creixent demanda d'energia, d'aliment, de béns, de serveis i d'informació de les poblacions humanes. Com a resultat, han sorgit noves inquietuds ecològiques, econòmiques, socials i geopolítiques. En aquest escenari, la detecció remota SAR és una eina potencial que proporciona informació única sobre les propietats i processos de la Terra que es pot utilitzar per resoldre reptes socials de dimensió local i global. Els SARs, que són sistemes coherents que poden proporcionar imatges d'alta resolució amb independència del temps, representen una alternativa adequada per a l'observació de la Terra. Alguns exemples d'àrees d'aplicació SAR són la topografia (generació de DEM amb interferometria), l'agricultura (classificació de cultius o humitat del sòl) o la geologia (monitoratge de deformació superficial). En aquest context, l'objectiu general del present doctorat ha estat part de la implementació i posterior avaluació de les capacitats de dos sensors SAR de banda X. D'una banda, el radar RISKSAR-X dissenyat per funcionar a terra i monitoritzar àrees d'observació a petita escala i, d'altra, el sensor ARBRES-X dissenyat per ser integrat en petits UAVs. Malgrat la seva concepció inherentment diferent, la concurrència d'ambdós sensors s'ha evidenciat al llarg d'aquest manuscrit. Aprofitant les similituds entre ells, s'han pogut avaluar de forma anàloga els dos sensors per obtenir conclusions. En aquest sentit, el vincle comú ha estat el desenvolupament del mode de funcionament polimètric OtF del RISKSAR-X, permetent que aquest sensor operi de forma equivalent a l'ARBRES-X. Pel que fa al sensor RISKSAR-X, s'han desenvolupat diverses contribucions hardware durant part d'aquest doctorat amb l'objectiu de millorar el rendiment del sistema. En dotar el sistema de la possibilitat d'operar en el mode d'adquisició totalment polarimètric OtF, s'ha reduït el relatiu llarg temps d'escaneig. Això és de gran interès ja que els blancs mesurats que presenten una reflectivitat variable a curt termini, com ara la vegetació en moviment, poden degradar els paràmetres extrets de les dades recuperades i la reconstrucció d'imatges SAR. Durant aquesta activitat doctoral s'ha estudiat el desenfocat de la imatge, la decorrelació i la degradació de la coherència introduïts per aquest efecte. A més, s'ha introduït un nou terme en la coherència interferomètrica diferencial que té en compte el desenfocat de la imatge. Pel que fa al sistema ARBRES-X, un dels principals objectius perseguits durant aquest doctorat ha estat la integració del sensor en un petit UAV MP superant les restriccions de pes, grandària i aerodinàmica de la plataforma. S'espera que l'ús d'aquest tipus de plataformes obri noves possibilitats en la detecció remota SAR aerotransportada, ja que ofereix molta més versatilitat que els UAV d'ales fixes habituals. S'han avaluat diferents estratègies de vol innovadores amb aquest tipus de plataformes i s'han obtingut resultats preliminars amb l'ús del sistema ARBRES-X. Durant el transcurs del present treball, s'ha dedicat molt esforç a assolir els primers resultats experimentals d'interferometria de múltiple passada obtinguts amb l'UAV MP conjuntament amb l'ARBRES-X. A més, el sensor ha estat dotat de capacitats totalment polarimètriques aplicant les millores desenvolupades al radar RISKSAR-X, el qual constitueix un altre exemple de la dualitat entre ambdós sistemes. Finalment, s'han realitzat amb èxit una apertura vertical i semicircular obtenint imatges SLC de l'escenari, el qual permet preveure la capacitat de l'UAV MP per a realitzar imatges tomogràfiques i apertures circulars completes en el futur. En conclusió, l'UAV MP és una plataforma prometedora que obre nous potencials per a diverses aplicacions, com ara la interferometria de múltiple passada o la tomografia diferencial amb la realització de trajectòries gairebé arbitràries.Postprint (published version